A frequent source of operating problems in refining and petrochemical processing units is the formation of deposits throughout those units resulting in an increase in pressure drop, decrease in efficiency, increase in energy consumption, loss of operating time, and other well-known difficulties. These deposits include salts of ammonia, inorganic contaminants that enter the process in the feed, and deposits that develop as by-products from corrosion of the processing unit including metal sulfides, metal oxides, metal hydroxides, and other metal salts. These deposits alone or in combination with other hydrocarbon polymers and decomposition products often form deposits that are difficult to remove from the internals of the processing units.
Another source of operating problems in refining and pertrochemical processing units is corrosion which is the result of the exposure of the metal surfaces to corrosive compounds that are frequently found in the stream being processed by the particular unit. Corrosion leads not only to the formation of unwanted deposits but also to metal and equipment failure.
Presently, film forming agents or filmers alone or in combination with dispersants are used to prevent the formation of deposits and/or the corrosion of the equipment of the various hydrocarbon processing units. Those film forming agents and/or dispersants, however, often do not function satisfactorily as fouling prevention agents and/or aggravate the conditions of the hydrocarbon processing unit.
One problem encountered is that the film forming agents or the dispersants, used alone or in combination, are unable to remove certain deposits that have a tendency to firmly affix onto the surface of the equipment. Those deposits usually consist of hydrocarbon polymers or decomposition products that are aggregated or glued together by salts and various metal compound by-products.
Another problem encountered is that the filmers used to prevent the fouling or the corrosion formation are not effective when the metal surface of the unit is covered by various types of deposits referred to above. Their ineffectiveness is due to the fact that the filmers are unable to form a tenacious complete film on the surface. Furthermore, the presence of deposits prevents the filmers from reaching the surface under the deposits, thereby allowing the corrosion under those deposits to proceed without control. Still another problem measureably encountered is that the filmers and/or the dispersants often cause the formation of an emulsion thereby resulting in process operating difficulties.
Another disadvantage of the filmers and/or the dispersants and the methods for using the same is that, under certain conditions, those filming agents and/or dispersants cause further deposit formations and promote fouling. That was usually attributed to thermal decomposition and unexpected chemical reaction of the filmer and/or the dispersant.
A further disadvantage of the filmers and dispersants presently used is that, due to the fact that large amounts of those filmers and dispersants are required to prevent fouling and corrosion in the unit, the product manufactured by the processing unit in question is sometimes contaminated with those filmers and dispersants.
All the aforementioned problems and disadvantages are overcome by the present invention by disclosing a method and composition for the complete removal and/or prevention of formation of deposits of ammonium salts and metal compounds by interacting those deposits with certain amines and oxygenated hydrocarbon compounds. As a result, the metal surfaces of the processing units remain clean thereby enabling the filming agents to form a tenacious and complete film on those surfaces and to effectively prevent the corrosion of those surfaces. The compositions disclosed by the present invention eliminate the use of dispersants and the formation of undesirable emulsions resulting therefrom. Furthermore, the compositions disclosed herein do not result in the formation of unexpected deposits or in the contamination of the products manufactured by the particular processing unit.
These and other advantages of the present invention will become apparent from the following description: